Turbocharger sub-assembly oil leaks are classified into 2 types. One is an internal oil leak, and the other is an external oil leak.

When oil leaks and smoke occur, the turbocharger may be mistakenly replaced, even though the turbocharger is not the cause of the problem.

When there are oil marks on the surface of the compressor housing, or oil in the compressor inlet or outlet, the problem may mistakenly be determined to be a turbocharger oil leak.

The parts of the turbocharger sub-assembly are shown in the following illustration.

*1

Compressor Housing

*2

Piston Ring (Seal Ring)

*3

Compressor Inlet

*4

Compressor Wheel

*5

Center Housing

*6

Turbine Shaft

*7

Oil Drain (Outlet)

*8

Compressor Housing O-ring

*9

Turbine Housing

*10

Turbine Wheel

*a

Internal oil leak to compressor housing

*b

Internal oil leak to turbine housing

*a

Fig. 1

-

-

Tip:

Above illustration is an example.

If there is an oil stain similar to the one shown in the illustration (fig. 1) on the turbocharger sub-assembly, it may be oil spray from parts surrounding the turbocharger sub-assembly or oil leaking from the air cleaner hose. Therefore, this kind of oil stain on the outer surface of the turbocharger sub-assembly is not caused by an oil leak from the turbocharger sub-assembly (external oil leak), and is not related to white smoke. For identification of an actual turbocharger sub-assembly outer oil leak, check only the sealing part shown in the following illustration.

*a

Fig. 2

*b

Fig. 3

*c

Oil Existence at Compressor Inlet (Max. 5 cm3)

*d

Oil Existence at Compressor Outlet

Tip:

Above illustration is an example.

A certain amount of oil exists in the intake system because blow-by gas containing oil mist is returned to the intake system by the PCV. Therefore, the oil amount at the compressor inlet shown in the left figure (fig. 2) is normal and not an oil leak from the turbocharger sub-assembly (internal oil leak). Oil at the compressor outlet as shown in fig. 3 is normal.

In addition, the compressor wheel surface may blacken due to blow-by gas but this is not abnormal.

*a

Fig. 4

*b

Oil Leak Check Point (compressor housing O-ring)

*c

In the case of an actual oil leak, oil leaks from the sealed part

-

-

Tip:

Above illustration is an example.

This illustration (fig. 4) is an example of an air leak test performed by applying soapy water to the area of the leak. Bubbles indicate the leak point.

Faults and Symptoms of Turbocharger Parts

Table 2. Compressor Side Piston Ring

Main fault

Piston ring (seal ring) breakage

Symptoms

Oil leaks to compressor housing

Excessive oil consumption

Note

In the case of compressor piston ring (seal ring) failure, a large amount of oil will be found between compressor outlet and intercooler, and between intercooler and intake manifold, but not found at compressor inlet.

If large amount of oil is found at the compressor inlet, it is not from the turbocharger and may indicate a problem in the PCV system.

Table 3. Turbine Side Piston Ring

Main fault

Piston ring (seal ring) breakage

Symptoms

Oil leaks to turbine housing

Large amount of white smoke from exhaust pipe

Excessive oil consumption

Note

In the case of turbine piston ring (seal ring) failure, a large amount of white smoke will be emitted continuously.

If white smoke is emitted only just after engine is started (and disappears later), or small amount of white smoke is emitted intermittently, it is not caused by the turbocharger sub-assembly. It is due to failure of other parts.

If wet oil is found at turbine inlet, it is not from turbocharger sub-assembly. It is due to problem in other parts.

Table 4. Center Housing (Oil Drain Clogging)

Main fault

Oil drain clogged by coked oil

Symptoms

Large amount of white smoke from exhaust pipe

Tip:

Oil coking is caused by insufficient oil maintenance.

If the oil drain is clogged by coked oil, oil cannot be drained smoothly, and it overflows from the center housing to the compressor housing and turbine housing. This results in a large amount of white smoke from the exhaust pipe.

If any solid (coked oil) is visually confirmed inside the center housing, it can be assumed to be the cause of internal oil leak.

*1

Oil Drain

-

-

*a

Coked Oil

*b

Oil Drain Clogged with Coked Oil

Tip:

Above illustration is an example.

Table 5. Turbine Shaft

Main fault

Breakage

Seizure

Symptoms

Shaft does not rotate

Oil leaks to compressor housing

Large amount of white smoke from exhaust pipe

Lack of power

Turbocharger noise changes

Note

In the case of turbine shaft failure, lack of power due to lack of boost pressure will be felt.

In cold conditions, shaft rotation can feel somewhat clingy due to viscosity of oil. Be sure not to mistake it for unsmooth shaft rotation.

Table 6. Compressor Wheel

Main fault

Breakage

Symptoms

Shaft does not rotate

Oil leaks to compressor housing

Lack of power

Note

In the case of compressor wheel failure, a large amount of oil will be found between the compressor outlet and intercooler, and between intercooler and intake manifold, but not found at the compressor inlet.

Oil is blocked by boost pressure at compressor piston ring (seal ring). Therefore, if boost pressure does not increase due to breakage of compressor wheel, oil will flow out to compressor housing.

Table 7. Compressor Housing O-ring

Symptoms

Oil leaks from compressor housing O-ring

Note

If an oil stain is separated by compressor housing O-ring, it can be determined to be due to oil spray from other parts surrounding turbocharger.

If an oil stain is traced to a hose connection part, it can be determined to be due to a hose connection failure.

*1

Compressor Back Plate

*2

Compressor Housing

*a

Oil Leak

*b

Oil Leak from compressor housing O-ring

Tip:

Above illustration is an example.

Table 8. Intake Hoses

Symptoms

Oil leaks from the hose connection between the hose and compressor housing

Note

If an oil stain is traced to an hose connection part, it can be determined to be due to hose connection failure.

When cleaning the electric EGR control valve assembly or diesel throttle body assembly, use a piece of cloth soaked with cleaning solvent. Spraying solvent directly onto these parts or soaking the parts in solvent may damage the parts.

Tip:

When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the GTS. Then after installing a new ECM, perform all of the initialization and registration procedures for the "Learning Values Write" function by following the instructions shown on the GTS display.

Check whether the white smoke is emitted only just after engine start, or not.

Tip:

If white smoke appears for only a short period of time immediately after the engine is started, the white smoke is not from the turbocharger sub-assembly.

If the turbocharger sub-assembly is the cause of the problem, regardless of whether the engine is cold or warmed up, there will be a large amount of white smoke emitted, to the extent that visibility will obstructed for a few meters by the smoke (as shown in the illustration).

Depending on whether there is oil mixed with the fuel, or whether there is unburned fuel present, the smell of the exhaust gas differs. When oil is mixed in, the exhaust gas smells like burning oil.

When cleaning the electric EGR control valve assembly, make sure the valve is completely closed.

Do not forcibly open the valve, as it may be damaged or deformed.

When cleaning the electric EGR control valve assembly, use a piece of cloth soaked with cleaning solvent. Spraying solvent directly onto these parts or soaking the parts in solvent may damage the parts.

Hold the electric EGR control valve assembly up to a light, and visually check that there is no gap between the valve and body.

OK

No light passes through (there is no clearance between the valve and body).

Tip:

If light passes through (there is a clearance between the valve and body), replace the electric EGR control valve assembly.

Light passes through part A shown in the illustration even if the valve is completely closed, this is not a malfunction.

*1

Electric EGR Control Valve Assembly

-

-

*a

Part A

*b

Clearance

*c

OK

*d

NG

Tip:

If any inspection result above is NG, check the EGR system, referring to the procedure for DTC P042E.

To check if the pistons and piston rings have malfunctioned, remove the oil level dipstick. If oil sprays out, the pressure inside the crankcase has risen which indicates that there is a malfunction in a piston or piston ring.

Check whether an excessive amount of wet oil or excessive oil deposits are present at the turbine inlet.

Tip:

Be sure not to mistake carbon soot for oil.

Result

Proceed to

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INSPECT TURBINE OUTLET

Check whether an excessive amount of wet oil or excessive oil deposits are present at the turbine outlet.

Tip:

Be sure not to mistake carbon soot for oil.

If the turbocharger shaft is tilted, some amount of oil will flow out from the center housing. Therefore, be sure not to mistake oil that flowed out from the center housing during or after the removal of the turbocharger sub-assembly for oil that was present before the removal of the turbocharger sub-assembly.

If an excessive amount of oil or excessive oil deposits are present at the turbine inlet, this oil is coming from the exhaust port of the cylinders, and may indicate a problem in 1 or more cylinders.